This invention generally relates to apparatus for determining the direction of a remotely-located signal source and, more particularly, to a system for determining the bearing of a remotely-located, underwater signal source.
One method for ascertaining the bearing of a remotely located soure of acoustic signals f(t) such as characteristic noise generated by boats or submarines and the like contemplates the use of an orthogonally-oriented pair of directional hydrophones wherein the one hydrophone provides an output signal varying as a function of both f(t) and the cosine of the angle of arrival .theta. and the other hydrophone provides an output signal varying as a function of both f(t) and sin.theta.. The ratio of the output signals provides a quantity which is a function of tangent of the bearing angle or angle of arrival .theta.. The use of conventional apparatus for time-compressing received signals in cases where the channels are not exactly matched can distort the amplitudes of the directional hydrophone output signals, introduce unequal signal-to-noise ratios and cause errors of impermissible magnitude in the computation of the bearing angle.